Why do people say 10 - 4 ? What is the meaning and origin?

Answer 1

It's a part of the '10' code system of radio etiquette that means 'messaged received' or 'affirmative.'

The '10' codes were developed in the 30's with the advent of short wave radio communications as a way of reducing the amount of talk time where only one person can talk at once and messages need to be quick. It was, and is still used by the military, police/emergency operations, film sets and just about any operation that uses 'walkie-talkies'. It's also a way as to not alert anyone who may be eavesdropping as to what is happening in the current operations if that person is not trained in the codes.

Currently the 10 codes are numbered from 10 - 1 (which means 'I'm receiving poorly/please repeat') all the way up to 10 - 200 which is a request for police presence at a specific location. The receiver of a 10 - 200 would ask the sender what their 10 - 20 (location) is. So the conversation might sound like this:

"Nation here, requesting 10 - 200, over." (It's Mickey, and I need some help here.)

"10 - 4, Nation. This is Catfish, what's your 10 - 20, over." (I understand, Mickey. Where are you?)

"Uhh...at the summit of a boreal trunk, gotta papa on my tail, this is a 911, over." (I'm hiding in the top of a tree, a bear has chased me up here, hurry up!)

"That was a 10 - 1, Nation. [chuckle] Please repeat, over." (What where you saying, Mickey? I didn't quite catch that.)

[long pause]

"10 - 26, Catfish. Over." (Nevermind.)

"10 - 4." (Okay.)

Answer 2

What Does 10-4 Mean

Answer 3

10-4 which means "affirmative", comes from the old 10 codes used by police and fire departments. Ten-codes were developed in the 1940s at a time when police radio channels were limited, to reduce use of speech on the radio.
They're currently being phased out.

Answer 4

See http://en.wikipedia.org/wiki/10-4 for an excellent explanation of what 10-4 means and its history.

Good Luck!!!

Answer 5

it means WHAT in trucker talk